In a batch processing apparatus that simultaneously processes a plurality of wafers with a gas, the gas is required to flow appropriately. Specifically, when the gas flows from a gas feeder to a gas discharger, it is not desirable for the gas to flow around the wafers, and it is desirable for the gas to mostly flow between the wafers. Moreover, when the gas to be fed to a certain wafer flows to another wafer, there is a risk that unevenness in processing between the wafers arises.